JP2828917B2 - Moisture-curable urethane sealant composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-melt type moisture-curable urethane sealant composition, and more particularly, to a moisture-curable urethane sealant composition having an excellent initial structural strength, which is suitable for bonding an automotive window glass. About.

[0002]

2. Description of the Related Art Conventionally, a polymer called a reactive hot melt, which is used in a heated and melted state, expresses initial physical properties by solidification accompanying a decrease in temperature, and exhibits final physical properties by a curing reaction. Compositions are known.

One example is a moisture-curable hot-melt type using a polyether polyol-based urethane prepolymer as a main component and using a polyol component as a raw material in combination with a polyester polyol and a polyether polyol. Sealing material (JP-A-02-3
No. 2189), a block type polymer obtained by reacting a urethane prepolymer containing a terminal isocyanate group with a thermoplastic saturated polyester polyol and a polyol having a molecular weight of 8000 or less and a diisocyanate compound reacted with a mixed polyol. Urethane prepolymer containing terminal isocyanate group (A)
And a urethane prepolymer containing terminal isocyanate groups (B), and a moisture-curable hot-melt adhesive (JP-A-03-590) having improved adhesion and initial elasticity after curing.
No. 84), a polyether polyol-based urethane prepolymer having a relatively low molecular weight and a glass transition temperature higher than room temperature, and a urethane prepolymer having a relatively large molecular weight and a glass transition temperature lower than room temperature. (See Japanese Patent Application Laid-Open No. 02-182774).

Further, in Japanese Patent Application Laid-Open No. Hei 6-88067, a sealant having a melting point of 30 to 100 ° C. and a diester ester compound mixed with a polyether polyol-based urethane prepolymer has a high initial strength and a wet heat deterioration. Seldom occurs.

JP-A-5-171035 discloses that a urethane prepolymer of a polyether polyol or a polyester polyol and an isocyanate is mixed with a urethane prepolymer (A) to a urethane prepolymer (A) in which all isocyanate groups are blocked with a monoalcohol. It describes that the obtained moisture-curable urethane sealant composition exhibits initial adhesive strength and is excellent in elasticity, adhesive strength and the like by curing in a relatively short time.

[0006] Such reactive hot melts are used in various fields, and particularly in the automobile industry.
It is useful as a sealant for attaching window glass to a vehicle body. And, the sealant for attaching the window glass, especially to improve workability, that it does not sag when applied to an adherend, initial physical properties sufficient to hold the window glass even in an uncured state, It is required to exhibit structural strength.

[0007]

However, the above-mentioned sealant using the urethane prepolymer has a high melting temperature at the time of application and has a poor stability at the time of heat such as an increase in viscosity due to heating. In addition, when a material having an isocyanate group blocked is added, there is a disadvantage that the properties of a cured product such as adhesiveness and physical properties of a rubber are reduced.

Accordingly, the present invention is a reactive hot melt which is particularly suitable for bonding a window glass of an automobile, has a high structural strength when not cured, and therefore has excellent coating properties and workability. An object of the present invention is to provide a moisture-curable urethane sealant composition having excellent adhesion.

[0009]

The present inventors have found that when a urethane prepolymer is added with a polyurethane compound in which a polyester polyol and a polypropylene ether polyol are reacted with hexamethylene diisocyanate and a part of which is blocked with a hydroxyl group, The inventors have found that a sealant composition having sufficient structural strength for coating can be obtained even at the time of curing, and have reached the present invention.

That is, the present invention relates to (1) a mixture of polyether triol and polyether diol having a number average molecular weight of 1,000 to 7000, a diisocyanate and an isocyanate group / hydroxyl group equivalent ratio of 1.1 to 2.5. Urethane prepolymer (A) reacted at a certain amount ratio
And (2) a polyester polyol having a number average molecular weight of 500 to 6000, and a number average molecular weight of 1000 to 7000
Is reacted with hexamethylene diisocyanate in an amount ratio such that the equivalent ratio of isocyanate group / hydroxyl group becomes 1.5 to 2.5, and further, a monoalcohol having 1 to 22 carbon atoms is converted into a hydroxyl group / isocyanate group. The polyurethane compound (B) added and reacted so that the equivalent ratio becomes 0.9 or less, and the content of the polyurethane compound (B) is 100 parts by weight of the urethane prepolymer (A). It is intended to provide a moisture-curable urethane sealant composition of 1 to 20 parts by weight.

Hereinafter, the present invention will be described in detail. The moisture-curable urethane sealant composition of the present invention contains a urethane prepolymer (A) and a polyurethane compound (B) as essential components.

(1) Urethane Prepolymer (A) The urethane prepolymer (A) used in the present invention is prepared by adding a diisocyanate to a mixture of a polyether triol and a polyether diol having a number average molecular weight of 1,000 to 7000 with an isocyanate group / hydroxyl group. Is equivalent to 1.1 to 2.
The reaction is carried out at a quantitative ratio of 5.

The mixture of polyether triol and polyether diol, one of the raw materials for producing the urethane prepolymer (A), is, for example, one or two alkylene oxides such as ethylene oxide, propylene oxide, butylene oxide and tetrahydrofuran. The above is addition-polymerized to a compound having two or more active hydrogens, and a mixture thereof is used as a triol having three hydroxyl groups per molecule or a diol having two hydroxyl groups per molecule. The reason for using polyether triol and polyether diol is to suppress foaming during moisture curing and to exhibit physical properties of a cured product.

Here, examples of the compound having two or more active hydrogens include polyhydric alcohols, amines, alkanolamines, polyhydric phenols and the like.
As polyhydric alcohols, ethylene glycol, propylene glycol, butanediol, diethylene glycol, glycerin, hexanetriol, trimethylolpropane, pentaerythritol, etc., as amines, ethylenediamine, hexamethylenediamine, etc., as alkanolamines , Ethanolamine, propanolamine and the like, and polyhydric phenols include resorcinol and bisphenols.

In producing the urethane prepolymer (A), a polyether polyol having a number average molecular weight of 1,000 to 7000 is used as a mixture of polyether triol and polyether diol. 100
If less than 0 is used, the viscosity of the prepolymer becomes too high to be practical. On the other hand, if it exceeds 7000, the properties of the sealant after curing become inferior. The mixing molar ratio of the polyether triol and the polyether diol in the polyether polyol is preferably 1: 3 to 3: 1 from the viewpoint of curability, viscosity, and physical properties of a cured product as a sealing agent.

Examples of the diisocyanate which is the other raw material for producing the urethane prepolymer (A) include various diisocyanates used in the production of ordinary polyurethane resins.
Specifically, 2,4-tolylene diisocyanate, 2,2
6-tolylene diisocyanate, phenylene diisocyanate, xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthalene-1,5
-Diisocyanates and hydrogenated compounds thereof,
Ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 1-
Methyl-2,4-diisocyanatocyclohexane, 1
-Methyl-2,6-diisocyanatocyclohexane,
Dicyclohexylmethane diisocyanate, triphenylmethane triisocyanate and the like.

These diisocyanates may be used alone or in combination of two or more when producing the urethane prepolymer (A).

In the production of the urethane prepolymer (A), the amount ratio of the raw materials is such that the equivalent ratio of the isocyanate group (isocyanate group / hydroxyl group) of the diisocyanate compound to the hydroxyl group of the polyether polyol is 1.1 to 2.
The ratio is set to 5. If the equivalent ratio is less than 1.1, the viscosity of the urethane prepolymer (A) becomes too high to be practically usable, while if it is more than 2.5,
Since a large amount of unreacted diisocyanate compound remains, the foaming resistance when used as a sealant decreases.

The production conditions for the urethane prepolymer (A) are not particularly limited, and ordinary production conditions for the urethane prepolymer may be used. That is, the reaction may be performed at a reaction temperature of about 50 to 100 ° C. under normal pressure. Also, organotin compounds,
A urethanization catalyst such as an organic bismuth compound may be used.

(2) Polyurethane compound (B) The polyurethane compound (B) used in the present invention comprises (i) a polyester polyol having a number average molecular weight of 500 to 6000 and a polypropylene ether polyol having a number average molecular weight of 1000 to 7000, Hexamethylene diisocyanate (HDI) is reacted at a ratio such that the equivalent ratio of isocyanate group / hydroxyl group becomes 1.5 to 2.5 to obtain a urethane prepolymer (b).
It is obtained by reacting 22 monoalcohols and adding them so that the equivalent ratio of hydroxyl group / isocyanate group becomes 0.9 or less.

(I) Production of urethane prepolymer (b) The polyester polyol used for the urethane prepolymer (b) is a polycondensate of a polybasic acid such as dicarboxylic acid and a polyhydroxy compound such as glycol. Polybasic acids include adipic acid, sebacic acid, phthalic acid, maleic acid, glutaric acid, and the like.Polyhydroxy compounds include ethylene glycol, diethylene glycol,
Butylene glycol, neopentyl glycol, hexane glycol, trimethylolpropane, glycerin,
Pentaerythritol and the like. Examples of the polyhydroxy compound include ethylene glycol, diethylene glycol, butylene glycol, neopentyl glycol, hexane glycol, trimethylolpropane, glycerin, and pentaerythritol. In addition to polycondensates, there are polycarbonate polyols having a structure in which alkylene groups are arranged via carbonate bonds, and lactone-based polyester polyols obtained by ring-opening polymerization of caprolactone monomers. A polyester polyol having a number average molecular weight of 500 to 6000 is used. When the one with less than 500 is used, the crystallinity becomes high and the melting point becomes high. On the other hand, when the one with more than 6000 is used, the adhesiveness to the adherend decreases, which is not preferable. Specifically, PCL-3000 manufactured by Daicel Chemical Industries, Ltd. may be used.

The polypropylene ether polyol used for the urethane prepolymer (b) is a polyol such as a diol or a triol obtained by addition polymerization of propylene oxide to a compound having two or more active hydrogens, and has a number average molecular weight. Is 1000 to 7000. Here, the compound having two or more active hydrogens is the same as the compound used when producing the polyether polyol of the urethane prepolymer (A). For example, Exenol 2020 manufactured by Asahi Glass Co., Ltd. can be used. If the number average molecular weight is less than 1,000, the viscosity of the urethane prepolymer increases,
On the other hand, if the amount exceeds 7000, the crystallinity of the reaction product becomes slow, and the initial physical properties of the sealant do not appear.
The reason why the polypropylene ether polyol is used as a component of the urethane prepolymer (b) is to improve the compatibility with the urethane prepolymer (A).

The molar ratio of the polyester polyol to the polypropylene ether polyol is preferably such that the ratio of the polyester polyol / polypropylene ether polyol is 1 to 10, particularly preferably 2 to 5. If it is less than 1, the initial strength is not exhibited, and if it is more than 10, the dispersibility of the polyester in the urethane compound (B) is deteriorated, and the adhesiveness is reduced.

The isocyanate used for the urethane prepolymer (b) is hexamethylene diisocyanate (HD
Use I). It is preferable to use HDI because the initial strength is improved.

In producing the urethane prepolymer (b), first, a polyester polyol and a polypropylene ether polyol are reacted with hexamethylene diisocyanate (HDI) to obtain a urethane prepolymer (b). The ratio is such that the equivalent ratio of the isocyanate group (isocyanate group / hydroxyl group) of HDI to the hydroxyl group of the polyol is 1.5 to 2.5. When the equivalent ratio is less than 1.5, the viscosity of the urethane prepolymer (b) becomes too high, and the compatibility with the urethane prepolymer (A) decreases. On the other hand, when the equivalent ratio is more than 2.5,
The crystallinity becomes slow, and the initial physical properties of the sealant do not appear.

The conditions for producing the urethane prepolymer (b) are not particularly limited, and ordinary production conditions for the urethane prepolymer may be used. That is, the reaction may be performed at a reaction temperature of about 50 to 100 ° C. under normal pressure. Also, organotin compounds,
A urethanization catalyst such as an organic bismuth compound may be used.

(Ii) Production of Polyurethane Compound (B) Next, the urethane prepolymer (b) is reacted with a monoalcohol to block a part of the isocyanate group to obtain a polyurethane compound (B).

The monoalcohol used for blocking the isocyanate group includes a linear or branched, aromatic, saturated or unsaturated monoalcohol having 1 to 22 carbon atoms. In addition, a linear saturated alcohol having 2 to 12 carbon atoms is preferable. Specific examples include methanol, ethanol, butanol, isobutanol, propanol, pentanol, hexanol, heptanol, octanol, stearyl alcohol, benzyl alcohol, 2-hydroxymethyl methacrylate, and the like.

Such a monoalcohol has an equivalent ratio of the hydroxyl group of the monoalcohol to the isocyanate group of the urethane prepolymer (b) (hydroxyl group / isocyanate group).
Is 0.9 or less, particularly 0.1 to 0.5.
When the ratio of the hydroxyl group / isocyanate group exceeds 0.9, the adhesiveness decreases. Furthermore, the case where the isocyanate group in the urethane prepolymer (b) is not blocked by a hydroxyl group is also included in the scope of the present invention.

Therefore, the polyurethane compound (B) used in the present invention comprises a polyester polyol having a number average molecular weight of 500 to 6000 and a polyester polyol having a number average molecular weight of 1000 to 7
2,000 polypropylene ether polyol and hexamethylene diisocyanate are reacted with an isocyanate group / hydroxyl group in an equivalent ratio of 1.5 to 2.5, or a polyester polyol having a number average molecular weight of 500 to 6000. Having a number average molecular weight of 1,000 to
7000 polypropylene ether polyol and hexamethylene diisocyanate are reacted at an isocyanate group / hydroxyl group equivalent ratio of 1.5 to 2.5, and a monoalcohol having 1 to 22 carbon atoms is further reacted with a hydroxyl group / isocyanate group. And a compound obtained by adding and reacting such that the equivalent ratio becomes 0.9 or less.

The conditions for the blocking reaction are not particularly limited. Normal urethanization reaction conditions may be used. That is, the reaction may be performed at a reaction temperature of about 50 to 100 ° C. under normal pressure.

Since the polyurethane compound (B) does not increase the viscosity of the sealant and does not lower the adhesiveness, it exhibits the initial physical properties of the sealant.

The moisture-curable urethane sealant composition of the present invention contains the urethane prepolymer (A) and the polyurethane compound (B) as essential components, and the amount ratio is 100 parts by weight of the urethane prepolymer (A). Against
The content of the polyurethane compound (B) is 1 to 20 parts by weight. When the content of the polyurethane compound (B) is less than 1 part by weight, initial physical properties are not exhibited. On the other hand, when the content is more than 20 parts by weight, adhesiveness is reduced and rubber properties of a cured product are hindered.

(3) Other Additives The moisture-curable urethane sealant composition of the present invention comprises, in addition to the above essential components, a plasticizer, a filler, a thixotropic agent, a tackifier, a catalyst, an ultraviolet absorber, It may contain one or more of dyes, pigments, flame retardants and the like.

Examples of the plasticizer include derivatives such as benzoic acid, phthalic acid, trimellitic acid, pyromellitic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, itaconic acid and citric acid, as well as polyesters, polyethers, and the like. Epoxy type and the like can be mentioned.

As the filler, silicic acid derivatives, talc,
Examples include metal powder, calcium carbonate, clay, and carbon black.

As the thixotropic agent, bentone, silicic anhydride,
Examples thereof include a silicic acid derivative and a urea derivative.

As the catalyst, dibutyltin dilaurate, dioctyltin laurate, zinc octylate,
Examples include metal-based catalysts such as organic bismuth compounds, and amine-based catalysts such as triethylenediamine and morpholine-based amines.

In a preferred embodiment of the moisture-curable urethane sealant composition of the present invention, the content of the polyurethane compound (B) is 1 to 20 parts by weight based on 100 parts by weight of the urethane prepolymer (A). And the total amount is 100% by weight, the urethane prepolymer (A) 20 to 70% by weight, the polyurethane compound (B) 1
Less than 4% by weight, less than 20% by weight of plasticizer, less than 60% by weight of filler, and less than 3% by weight of other components.

One example of the production of the moisture-curable urethane sealant composition of the present invention is shown below. A urethane prepolymer (A) and a urethane compound (B) are charged into a kneading machine filled with nitrogen gas. After adding a plasticizer, a filler and the like according to the above, kneading is sufficiently performed under reduced pressure. Thereafter, a catalyst may be added and kneaded as needed. The obtained moisture-curable urethane sealant composition may be applied to the adherend in a molten state as it is, or may be poured into a container, then cooled and sealed, and stored. The stored composition,
Heat and melt again before use.

As an example of a method for applying the moisture-curable urethane sealant composition of the present invention, at about 50 to 60 ° C.
After applying the moisture-curable urethane sealant composition to one or both of the adherends, they are adhered to the adherend by cooling and solidification. When the moisture-curable urethane sealant composition of the present invention is used, after cooling and solidifying, it immediately exhibits sufficient structural strength to be mounted on an adherend such as a glass plate, and is further cured by moisture. Thereby, the physical properties of the cured product (elasticity, adhesive strength, etc.) are developed.

[0042]

EXAMPLES The present invention will be specifically described below with reference to examples.

(Examples 1 to 11 and Comparative Examples 1 to 6)
The following urethane prepolymer (A) and polyurethane compound (B) were synthesized, and a moisture-curable urethane sealant composition shown in Table 1 containing them was produced. With respect to them, initial physical properties were measured and evaluated, and the results are shown in Table 1. The viscosities of the compositions of Examples 2, 4, 6 and Comparative Example 4 were measured at 20 ° C. and 60 ° C. The viscosity of the composition of Example 2 is 1410 Ps,
230 Ps at ° C. The viscosity of the composition of Example 4 is
It was 1630 Ps at 20 ° C. and 250 Ps at 60 ° C.
The viscosity of the composition of Example 6 was 1320 Ps at 20 ° C., 6
It was 220 Ps at 0 ° C. The viscosity of the composition of Comparative Example 4 was 600 Ps at 20 ° C. and 210 Ps at 60 ° C.

(Production of urethane prepolymer (A)) 57 parts by weight of polyoxypropylene triol having an average molecular weight of 5,000 having three hydroxyl groups and polypropylene ether diol 2 having an average molecular weight of 2,000 having two hydroxyl groups
3 parts by weight were placed in a reaction vessel, dehydrated under reduced pressure at 110 ° C. and 50 mmHg for 2 hours, and then cooled to 80 ° C.
9.1 parts by weight of a mixture of tolylene diisocyanate and 2,6-tolylene diisocyanate (80:20) was added with stirring, and reacted until free isocyanate reached 2.2% to obtain a TDI prepolymer. . Next, diphenylmethane-4,4 'was added to the TDI prepolymer.
-Add 19.6 parts by weight of diisocyanate, stir and add 85 parts by weight of polyoxypropylene triol having an average molecular weight of 5,000 and 35 parts by weight of polypropylene ether diol having an average molecular weight of 2,000 which have been dehydrated in advance. The reaction was carried out until the concentration reached 0.8% to obtain an MDI prepolymer to obtain a urethane prepolymer (A).

(Production of Polyurethane Compound (B)) Polycaprolactone polyol having an average molecular weight of 3000 (PC
L-3000) and a polypropylene ether polyol having an average molecular weight of 2,000 (Exenol 2020) in the molar ratio and amount shown in Table 1 below.
After dehydration under reduced pressure of 50 mmHg at 50 ° C. for 2 hours, the mixture was cooled to 80 ° C., and a predetermined molar ratio of hexadimethylene diisocyanate shown in Table 1 was added to the polyol mixture with stirring to cause a reaction. Isocyanate 1
A predetermined amount (molar ratio) of ethanol shown in Table 1 was added to the mole, and the reaction was carried out until free isocyanate was no longer present to obtain each polyurethane compound.

(Production of a moisture-curable urethane sealant composition) In a kneader container filled with nitrogen, 100 parts by weight of the urethane prepolymer (A) and a predetermined amount of each of the polyurethane compounds (B) shown in Table 1 below. Plasticizer (compound name: trioctyl trimellitate)
20 parts by weight, 100 parts by weight of dry carbon black, and 10 parts by weight of dry calcium carbonate were charged and kneaded sufficiently under reduced pressure. Then, 1.7 parts by weight of a 5% dioctyl phthalate solution of dioctyl tin dilaurate was added and sufficiently kneaded under reduced pressure to obtain a composition. Each of the obtained compositions was subjected to the following physical property tests.

1. Evaluation of H-type initial physical properties The H-type initial physical properties measurement method is to keep each composition at 60 ° C,
Fused on a glass adherend, sandwiched between glass plates until the adhesion thickness becomes 6 mm, and 10 ° C at 20 ° C and 65% RH.
After standing for minutes, the H-type tensile strength was measured. Table 1 shows the results. 2. Evaluation of Adhesiveness Glass Primer G manufactured by Yokohama Rubber Co., Ltd.
(G-20) was coated on a coated steel plate with a primer M (M-300) for a coated steel plate manufactured by Yokohama Rubber Co., Ltd., and the sealant compositions manufactured in Examples and Comparative Examples were applied to a thickness of 3 mm. Then, it was left in an environment of 20 ° C. and 65% RH for 7 days to prepare an adhesion test piece. While cutting the cured adhesive test piece into the obtained adhesive test piece, the cured test piece was observed for tensile fracture surface and evaluated according to the following criteria.

Evaluation criteria CF: Material fracture PS: Interfacial peeling

[0049]

[Table 1]

[0050]

[Table 2]

[0051]

Industrial Applicability According to the present invention, a reactive hot melt particularly suitable for bonding a window glass of an automobile, which has excellent structural strength when uncured, has a sufficient adhesiveness to glass and painted steel sheet. There is provided a moisture-curable urethane sealant composition having the formula: Therefore, when the moisture-curable urethane sealant composition of the present invention is used, the workability is improved, and in particular, the effect that the production time can be shortened with rapid development of the initial physical properties is obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI C08L 75/04 C08L 75/04 C09J 175/04 C09J 175/04 (72) Inventor Go Nishida 2-1 Oiwake, Hiratsuka-shi, Kanagawa No. Yokohama Rubber Co., Ltd. Hiratsuka Works (56) References JP-A-7-196913 (JP, A) JP-A-5-171035 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) C09K 3/10 C08G 18/10 C08G 18/42 C08G 18/48 C08G 18/65 C08L 75/04 C09J 175/04

Claims (1)

(57) [Claims] (1) The number average molecular weight is from 1,000 to 7000
A mixture of a polyether triol and a polyether diol with a urethane prepolymer (A) obtained by reacting a diisocyanate with an isocyanate group / hydroxyl group equivalent ratio of 1.1 to 2.5, and (2) A) Polyester polyol having a number average molecular weight of 500 to 6000, and hexamethylene diisocyanate to a polypropylene ether polyol having a number average molecular weight of 1000 to 7000,
The isocyanate group / hydroxyl group is reacted at an equivalent ratio of 1.5 to 2.5, and a monoalcohol having 1 to 22 carbon atoms is further reacted with a hydroxyl / isocyanate equivalent ratio of 0.1 to 2.5.
The polyurethane compound (B) is added and reacted so as to be 9 or less, and the content of the polyurethane compound (B) is 1 to 20 parts by weight based on 100 parts by weight of the urethane prepolymer (A). A moisture-curable urethane sealant composition, characterized in that: